Objective To review the relationship between the immune system and the mechanism of pain. Data sources Related researches published in the period of 1987-2005 were systematically reviewed. Study selection Articles about the immune system and pain were selected. Data extraction Data were mainly extracted from 74 articles which are listed in the reference section of this review. Results Pain was classically viewed as being mediated solely by neurons. However, growing evidence has showed the possible relationships between the immune system and the central nervous system. In this article, we reviewed the role of the immune system in the development of pain, together with the importance of the glia in this process. These findings suggest a novel approach to pain control in the future. Conclusions The immune system plays a potential but important role in the development of pain. Objective To review the relationship between the immune system and the mechanism of pain. Data sources Related researches published in the period of 1987-2005 were systematically reviewed. Study selection Articles about the immune system and pain were selected. Data extraction Data were mainly extracted from 74 articles which are listed in the reference section of this review. Results Pain was classically viewed as being mediated solely by neurons. However, growing evidence has showed the Possible relationships between the immune system and the central nervous system. In this article, we reviewed the role of the immune system in the development of pain, together with the importance of the glia in this process. These findings suggest a novel approach to pain control in the future. Conclusions The immune system plays a potential but important role in the development of pain.